The present invention relates to powered roller conveyor systems and, in particular, straight sections, 90 degree sections, and 180 degree sections thereof.
A. Powered Roller Conveyor Systems: Straight Sections
A conventional straight section of a powered roller conveyor system is shown in drawing 1 of the '002 publication and includes pulleys and a belt. A partially disassembled conventional straight section of a powered roller conveyor system is shown in drawing 2 of the '002 publication, and is similar in structure and operation to that shown in drawing 1 of the '002 publication. Another partially disassembled conventional straight section of the powered roller conveyor system of drawing 2 of the '002 publication is shown in drawing 3 of the '002 publication, and a pulley and associated components of that powered roller conveyor system are shown in drawing 4 of the '002 publication.
One conventional method of powering a roller is to use an internal motor. A good example of an internally powered roller is the motorized roller shown in drawing 5 of the '002 publication, which is manufactured by Itoh Denki of Hanover Township, Pa. under model number PM486FS. The internally powered roller shown in drawing 5 of the '002 publication includes two groves, each one designed to receive a loop of some kind, ranging from a rubber band to an O-ring, chain, belt, tube, strand, cord or cable (hereinafter referred to generally as a “loop”). The loop extends to an adjacent roller for indirectly driving the adjacent roller. A powered roller conveyor system is shown in drawing 6 of the '002 publication, in which rollers are internally powered and include loops and grooves for driving other rollers.
While less expensive than an internally powered roller, the non-powered rollers are more expensive than regular rollers due to the groves and the loops, which creates the need for a lot of parts and creates subsequent maintenance issues.
Another method is to drive one or more of the roller with an exterior motor. The motor pulls a loop that is engaged with and directly drives one or more of the rollers, and some of the rollers are not driven by such loop and, instead, are driven by secondary loops that extend between such rollers and the directly driven rollers. For example, an external motor may drive a single roller via a chain, and additional chains and sprockets may be used for other rollers to be driven by such single roller. An exemplary chain-driven powered roller conveyor is shown in drawings 7-8 of the '002 publication. Each roller includes two sprockets and is connected by respective chains to adjacent rollers.
Another way of powering a conveyor includes using an external motor that rotates a drive shaft that runs the length of the conveyor. A respective loop extends from the shaft to each roller, and the loop twists in a figure eight whereby the shaft and the rollers rotate perpendicular to one another. Drawings 9-11 of the '002 publication illustrate such a powered roller conveyor system.
Yet another conventional way to drive a powered roller conveyor is to use a loop that extends under and frictionally engages the surfaces of the driven rollers. A belt may be used that is flat or may include a “V” or “U” cross-sectional profile. An exemplary powered roller conveyor that utilizes a loop in the form of a wide and flat belt to frictionally engage and drive rollers is shown in drawings 12-14 of the 002 publication.
B. Powered Roller Conveyor Systems: 90 Degree Curved Sections
Curved power roller conveyors are more complicated to design and build, especially with the conventional use of pulleys, compared to straight section powered roller conveyors.
A 90 degree curved section of a conventional powered roller conveyor system is shown partially disassembled in drawing 15 of the '002 publication. Drawings 16-17 of the '002 publication also illustrate partially disassembled views of another, similar 90 degree curved section of a conventional powered roller conveyor system.
In use, it is difficult to keep the loop on and tracking correctly, and the pulley system creates drag which causes the loop (if extensible) to stretch and eventually fall off.
Additionally, it will be appreciated that in conventional 90 degree curved sections of powered roller conveyor systems, the last roller in a curved section is indirectly driven by tying the last roller with a prior driven roller, again using a loop of some kind. Normally the rollers that are looped together have a special crimp into which the loop of material is placed, which enables the loop to track correctly and stay in place.
C. Powered Roller Conveyor Systems: 180 Degree Curved Sections
A 180 degree curved section of a conventional powered roller conveyor system is shown partially disassembled in drawing 18 of the '002 publication.
As will be appreciated, the drive mechanisms of these foregoing conventional ways tend to follow the curve, which is believed to be a significant contributor to the expense thereof, as following the curve requires more parts in tracking the curve and more labor in assembly.
Various ways exist to power 180 degree and 90 degree curved sections of powered roller conveyors. One way is to power all of the pulleys. Another way is to use a tapered roller, which can be the internal motor type or driven by a loop (e.g., belt, chain, etc.). This is generally expensive. A third way is to use a series of drive shafts that are coupled together with “U” joints. Normally the shaft drives the rollers by the twisted, figure “8” loops. Curved sections of conventional powered roller conveyor systems that utilize U joints are represented in drawing 19 of the '002 publication.
Due to space constraints, extra cost or other reasons, it is often common to directly drive only a subset of the rollers directly by the power source—rather than directly drive all of the rollers—in a powered roller conveyor. In such cases, the other rollers are driven by indirect means.
Additionally, it will be appreciated that, like in with 90 degree curved sections, in many conventional 180 degree curved sections of powered roller conveyor systems, the last roller in a curved section is indirectly driven by tying the last roller with a prior driven roller using a loop. Normally the rollers that are looped together have a special crimp into which the loop of material is placed, which enables the loop to track correctly and stay in place.
As will be appreciated by those having ordinary skill in the art, the straight sections of powered roller conveyors are much easier to make and use compared to the 90 degree and 180 degree curved sections of powered roller conveyors. The curved sections have many additional parts, it is difficult to keep the loop on and tracking correctly in such conveyors, and the pulley system in the curved section of such conveyors creates drag which causes the loop to stretch (if extensible) and fall off.